DE60023298T2 - MAGNETIC RECORDING FILM AND BASIC FILM THEREFOR - Google Patents

Description

Field of invention

The The present invention relates to a magnetic recording medium and a base film for this. in the In particular, the invention relates to a magnetic recording medium with excellent electromagnetic conversion properties and a small reduction in output with repeated use as well a base film for this.

description of the prior art

In Recent years have seen remarkable progress the increase the density of a magnetic recording medium has been made, and the development and implementation of a ferromagnetic metal thin film magnetic recording medium, comprising a thin one Film made of a ferromagnetic metal, formed on a non-magnetic Base sheet by a physical deposition method, e.g. vacuum deposition or sputtering or plating, are now underway. For example are a co-deposition band (JP-A 54-147010) (herein, the term "JP-A" means a "Laid-Open Publication Japanese Patent Application ") and a magnetic recording medium with a Co-Cr alloy for vertical recording (JP-A 52-134706).

There conventional coated magnetic recording media (magnetic Recording media comprising a magnetic layer formed on a non-magnetic base film by mixing magnetic powders with an organic polymer binder and applying the resulting Mixture) have a low recording density and a large recording wavelength, The magnetic layer has a large thickness of about 2 μm or more on. In contrast, a metal thin film, which by means of the Thin film formation, e.g. Vacuum deposition, sputtering or ion plating, is formed, a very small thickness of 0.2 μm or less.

at Thus, the above-mentioned high-density magnetic recording medium exercises the surface condition a non-magnetic base film has a great influence on the surface properties a magnetic recording layer. That is, the surface condition The non-magnetic base film appears directly as unevenness the surface the magnetic recording layer, the noise in recording and playback signals. The surface of the non-magnetic For this reason, base film is desirably possible smooth.

on the other hand it is from the viewpoint of handling properties such as Transport, scratching, unwinding and winding in the education a non-magnetic base film and in the film forming process so that when too big smoothness the surface the film's lubricity between films is deteriorated, resulting in a reduction of Product yield and an increase the production costs. From the point of view of production costs is the surface the non-magnetic base film therefore as rough as possible.

The surface The non-magnetic base film should therefore from the point of view Electromagnetic conversion characteristics smooth, under that Aspect of handling properties and production costs be rough on the other hand.

Further becomes in the case of a metal thin film magnetic recording medium a treatment called "ion bombardment" carried out, the surface a base film is activated by ions before forming a metal thin film will to the adhesion between the metal thin film and the base film to improve.

Because while making this metal thin film High-temperature heat Applied to the front of the film is the back the film cooled, to melt the base film or worsening the physical Properties, e.g. the mechanical properties of the film too prevent. For cooling the back the film becomes the base film frequently around a drum-like cooling material wound. In this case, both ends of the base film are masked to the formation of a metal thin film on the surface to prevent the drum.

Accordingly, there always exists an area whose surface is activated by ion bombardment and free from a metal thin film exposed at both ends to the above-mentioned deposition step Sample roll in the longitudinal direction. When the film is rolled, this area is brought into contact with the opposite side of the film at high pressure, which makes it easy to block. In order to produce a metal thin film magnetic recording medium, after the deposition of a metal thin film, a back layer layer and optionally a cover layer layer are formed. If the above blocking occurs in the step of processing these layers, the base film will easily break or wrinkle, with the result of a large reduction in the yield.

to solution of the above problem, JP-A 9-207290 and JP-A propose 9 226063 a laminated film consisting of a layer A and from a layer B, whose surface rougher than the surface situation A. However, this procedure may have a reduction in output with repeated use and occurrence of the above-mentioned blocking do not suppress albeit the electromagnetic conversion characteristics, handling characteristics and winding properties can be compensated to some extent.

Summary the invention

A Object of the present invention is to provide a laminated thermal load base film for magnetic recording media, which overcomes the above deficiency of the prior art, excellent anti-blocking properties, winding properties and processability and to a metal deposition thin film magnetic recording medium leads, which has excellent electromagnetic conversion properties having.

A Another object of the present invention is to provide a magnetic recording medium which is a magnetic Layer on the above-mentioned base film according to the present invention comprises and excellent characteristic properties, e.g. excellent electromagnetic conversion properties.

Further Objects and advantages of the present invention will become apparent the following description.

According to the present The invention firstly the above-mentioned objects and advantages of the present invention achieved by a laminated thermoplastic base film for a magnetic recording medium (hereinafter also referred to as "base film according to the present invention Invention ", consisting of a first thermoplastic layer with a surface roughness WRa of the exposed surface from 0.1 to 4 nm and a second thermoplastic layer, the 0.001 to 5% by weight of third inert fine particles having an average particle diameter the primary particle from 0.1 to 2.0 μm and 0.001 to 10 wt .-% of an ester wax from an aliphatic Monocarboxylic acid containing 8 or more carbon atoms and a polyhydric alcohol, and the a water contact angle of the exposed surface of 70 to 90 °, wherein the first thermoplastic layer and the second thermoplastic layer on each other laminated.

Secondly The above objects and advantages of the present Invention achieved by a magnetic recording medium, which the base film according to the present Invention as a base film and a magnetic film formed on the base film Location has.

detailed description of the preferred embodiments

It will now be first the base film according to the present Invention described. in the case of a diol component or the whole all dicarboxylic acids and oxycarboxylic acids in the case of a dicarboxylic acid component and an oxycarboxylic acid component.

Further can be a polyfunctional compound with a functionality of 3 or more, e.g. trimellitic or pyromellitic acid, be copolymerized. In this case, the connection can be in one be copolymerized in such amount that the polymer substantially is linear, e.g. 2 mol% or less based on the whole all dicarboxylic acid components.

The polyester film of the present invention (hereinafter also referred to as "polyester layer A") contains first inert fine particles (hereinafter also referred to as "inert particles A"). Examples of the inert particles A include heat-resistant organic polymer fine particles such as cross-linked silicone resin, cross-linked polystyrene, cross-linked styrene-divinylbenzene copolymer, polymethyl methacrylate, methyl methacrylate copolymer, cross-linked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride, Polyacrylonitrile and benzoguanamine resin; and inorganic compounds such as silica, alumina, titania, kaolin, talc, graphite, calcium carbonate, feldspar, molybdenum disulfide, carbon black and barium sulfate.

Of the average particle diameter of the primary particles of the inert particles A is 30 to 120 nm, preferably 35 to 110 nm, more preferably 40 to 100 nm. When the average particle diameter is smaller than 30 nm, can not obtain satisfactory running durability and when the average particle diameter is larger than 120 nm, the electromagnetic conversion characteristics deteriorate.

With regard to the shape of the inert particles A, the volume-forming coefficient (f) represented by the following equation (I) is 0.1 to π / 6, preferably 0.3 to π / 6, more preferably 0.4 to π / 6. f = V / D 3 (I) where f is a volume forming coefficient, where V is the volume (μm ³ ) of the particle and where D is the maximum diameter (μm) of the projection plane.

The inert particles A with a volume-forming coefficient (f) of π / 6 are globular (spherical). This means, the inert particles A having a volume-forming coefficient (f) of 0.4 to π / 6 are essentially globular, spherical or oval like a rugby ball and are particularly preferred. The particles with a volume forming coefficient (f) of less than 0.1, e.g. flake-like particles adversely affect the running durability.

The density of protrusions derived from the inert particles A on the surface of the polyester layer A is 5,000 to 50,000 / mm ² , preferably 7,500 to 45,000 / mm ² , more preferably 10,000 to 40,000 / mm ² . When the density of the projections derived from the inert particles A on the surface is smaller than 5,000 / mm ² , the friction of the magnetic layer with the magnetic head becomes high and the running durability of the magnetic layer with repeated use deteriorates disadvantageously. If the density of the protrusions is higher than 50,000 / mm ² , more protrusions will fall off, disadvantageously resulting in more drop-outs.

The Density of the projections can be adjusted via the concentration and / or amount of a glycol slurry of Particles added in the polymerization of the polyester becomes.

The Agglomeration rate of the inert particles A on the surface of the Polyester layer A is 4 to 20%, preferably 5 to 18%, more preferably 6 to 16%, especially preferably 7 to 14%. When the agglomeration rate of the particles becomes smaller is 4%, the running durability becomes repeated use unsatisfactory and there is a significant reduction in output. If the agglomeration rate higher is than 20%, the electromagnetic conversion characteristics deteriorate.

The Agglomeration rate of the particles can be adjusted via the Adjustment of the pH of the abovementioned glycol slurry Particles added in the polymerization of the polyester and their reaction or over the setting of the reaction process, the temperature and the injection speed for injecting the above slurry.

A another layer, e.g. a coating layer or a further polyester layer, can be on one side or both sides of the first base film according to the present Invention be formed in the limits in which it is for the task is not detrimental to the present invention, so the characteristic Properties of a magnetic tape, e.g. the handling properties in the production and processing, to improve.

For example, in the production of a magnetic tape from the first base film of the present invention, a first coating layer (hereinafter also referred to as "coating layer B"), the second inert fine particles (hereinafter also referred to as "inert particle B") with an average Particle diameter of 10 to 50 nm and a volume-forming coefficient of 0.1 to π / 6 formed on the magnetic layer side of the inert particle A containing polyester layer A formed to a reduction in output (durability against deterioration in the silent mode), caused by repeated contact with the magnetic head, to prevent. Preferably, the above-mentioned coating layer B has a density of protrusions derived from the inert particles B on the surface of 2,000,000 to 20,000,000 / mm ² and a surface roughness (Ra) of 0.1 to 2.0 nm.

The In the above-mentioned coating layer B contained inert particles B are preferably inert particles which are present in a coating solution only settle hard and have a relatively low relative density. Preferred examples of The inert particles B include heat-resistant polymer particles made of materials such as cross-linked silicone resin, cross-linked acrylic resin, cross-linked polystyrene, Melamine-formaldehyde resin, aromatic polyamide resin, rolyamide imide resin, crosslinked polyesters and wholly aromatic polyesters, silica (Silica) and calcium carbonate. Particularly preferred are crosslinked Silicone resin particles, core-shell organic particles (Core: cross-linked polystyrene, shell: Polymethylmethacrylate) and silica.

Of the average particle diameter of the primary particles of the inert particles B is 10 to 50 nm, preferably 15 to 45 nm, more preferably 20 to 40 nm. When the average particle diameter is smaller than 10 nm, the slipperiness can the resulting film unsatisfactory, and if the average Particle diameter is larger than 50 nm the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The inert particles B have a volume-forming coefficient (f) of 0.1 to π / 6, preferably 0.2 to π / 6, more preferably 0.3 to π / 6, particularly preferably from 0.4 to π / 6 on. Particles with a volume-forming coefficient (f) of less as 0.1, e.g. flake-like particles, make it more difficult, the effect the improvement of the gliding ability to obtain the film.

The density of protrusions derived from the inert particles B on the surface of the coating layer B is 2,000,000 to 20,000,000 / mm ² , preferably 3,000,000 to 15,000,000 / mm ² , more preferably 3,500,000 to 12,000,000 / mm ² . If the density of the protrusions on the surface of the coating layer B is smaller than 2,000,000 / mm ² , the slipperiness of the obtained film may be unsatisfactory, and if the density of the protrusions is higher than 20,000,000 / mm ² , the electromagnetic conversion characteristics of the obtained magnetic recording medium fail unsatisfactory.

The surface roughness (Ra) of the coating layer B is 0.1 to 2.0 nm, preferably 0.2 to 1.8 nm, more preferably 0.3 to 1.6 nm. When the surface roughness (Ra) is smaller than 0.1 nm, the slipperiness of the obtained film may be unsatisfactory fail, and if the surface roughness is larger than 2.0 nm the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The surface roughness (Ra) can be adjusted via the particle diameter and / or the amount of in the coating layer B to be incorporated inert particles B.

For the coating layer B, a binder resin is used to bind the inert particles B. The binder resin is preferably an aqueous polyester resin, aqueous Acrylic resin or aqueous Polyurethane resin, more preferably an aqueous polyester resin.

Examples for the aqueous Polyester resins include polyester resins each consisting of at least a polycarboxylic acid, e.g. isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6- 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, sodium 5-sulfoisophthalate, Potassium 2-sulfoterephthalate, trimellitic acid, trimesic acid, monopotassium salt of trimellitic or p-hydroxybenzoic acid, as the acid component and at least one polyhydroxy compound, e.g. ethylene glycol, Diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, p-xylylene glycol, dimethylolpropane or bisphenol A adduct with ethylene oxide, as a glycol component; Graft polymers and block copolymers prepared by bonding an acrylic polymer chain to a polyester chain; and acrylic modified polyester resins comprising two different polymers, the one specific physical structure in the microparticle (Type IPN (interpenetrating polymer network) or type core-shell). The watery Polyester resin can be of any type in water soluble, emulsifiable or finely dispersible. A sulfonate group, carboxylate group or polyether unit can in the molecule introduced the polyester resin to provide a hydrophilic nature.

Possible and it is preferred to use a coating layer and / or a further polyester layer to form on the opposite side of the magnet sheet, When a magnetic tape made of the polyester film according to the present invention should be to the handling properties in the production and processing of the film.

If e.g. a second coating layer (hereinafter also referred to as "coating layer C "), the fourth inert fine particles (hereinafter also referred to as "inert particles C") with an average particle diameter of the primary particles from 20 to 80 nm on the magnetic layer side opposite Side is formed when a magnetic tape from the polyester layer A, which contains the inert particles A, is to be produced, and the above-mentioned coating layer C has a surface roughness (Ra) of 2.5 to 10.0 nm and a thickness of 8 to 50 nm, can the handling properties are improved without the effect detrimental to the present invention to influence.

Examples for the in the above-mentioned coating layer C aufzunehmenden inert Particles C are the same as those for the above inerts Particle B listed.

Of the average particle diameter of the primary particles of the inert particles C is 20 to 80 nm, preferably 30 to 70 nm, more preferably 40 to 60 nm. When the average particle diameter is smaller than 20 nm, the slipperiness can the resulting film unsatisfactory, and if the average Particle diameter is larger than 80 nm, can the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The surface roughness (Ra) of the coating layer C is 2.5 to 10.0 nm, preferably 3.0 to 9.0 nm, more preferably 3.5 to 8.0 nm. When the surface roughness (Ra) is smaller than 2.5 nm, the slipperiness of the obtained film may be unsatisfactory fail, and if the surface roughness is larger than 10.0 nm, can the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The Thickness of the coating layer C is 8 to 50 nm, preferably 9 to 40 nm, more preferably 10 to 30 nm. When the thickness of the coating layer C is less than 8 nm, can the inert particles fall off and when the thickness is greater than 50 nm, the running durability of the obtained tape can be unsatisfactory fail.

Examples for the Binder resin for bonding the above-mentioned inert particles C. the same as the one for the above inert particles B are listed.

Of the Coating layer C may be an alkylcellulose or siloxane copolymerized Added acrylic resin the strength of the coating film and the antiblocking properties to improve.

At Position of the above-mentioned coating layer C may be another polyester layer used to accomplish the same purpose.

If e.g. a second polyester layer (hereinafter also referred to as "polyester layer D (rough Position) "), the third inert fine particles (hereinafter also referred to as "inert particles D") with an average particle diameter of the primary particles from 0.1 to 2.0 μm formed on the magnetic layer side opposite side when a magnetic tape from the polyester layer A (flat position), which contains the inert particles A, is to be produced, and the above-mentioned polyester layer D has a surface roughness (Ra) of 2.5 to 10.0 nm and has a thickness of preferably 0.1 to 2.0 microns, can the handling properties are improved without the effect detrimental to the present invention to influence.

Examples for the Polyester of the above-mentioned polyester layer D are the same as the for the above-mentioned polyester layer A listed. The polyester of Polyester layer D may differ from the polyester of the polyester layer A. but is preferably the same as that for the polyester layer A.

Examples for the in the above-mentioned polyester layer D to be absorbed inert particles D are the same as those for the above inert particles A are listed.

Of the average particle diameter of the inert particles D is 0.1 to 2.0 μm, preferably 0.2 to 1.5 μm, more preferably 0.3 to 1.0 μm. If the average particle diameter is smaller than 0.1 μm, then slipperiness the resulting film unsatisfactory, and when the average particle diameter is larger than 2.0 μm, can the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The inert particles D may consist of one type of particles or a mixture of two or more different types of particles. If the inert particles D consist of two or more different Ar consisting of particles, particles having an average particle diameter of the primary particles of 0.1 to 2.0 μm and fine particles having an average particle diameter of the primary particles of 0.01 to 0.1 μm, for example, colloidal silica or alumina having an α-, γ, δ or θ crystal form, preferably used. Of the above examples of the inert particles A, fine particles having an average particle diameter of the primary particles of 0.01 to 0.1 μm can be further used.

Of the Fine particle content is preferably from 0.001 to 5% by weight, more preferably from 0.005 to 1% by weight, particularly preferably 0.01 to 0.5 wt .-%.

The surface roughness (Ra) of the polyester layer D. 2.5 to 10.0 nm, preferably 3.0 to 9.0 nm, more preferably 4.0 to 8.5 nm. When the surface roughness (Ra) is smaller than 2.5 nm, the slipperiness of the obtained film may be unsatisfactory fail, and if the surface roughness (Ra) is larger than 10.0 nm, can the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The Thickness of the polyester layer D is preferably 0.1 to 2.0 μm, more preferably 0.2 to 1.5 μm, much more preferably 0.3 to 1.2 μm. If the thickness is less than 0.1 μm, the inert particles may fall off, and if the thickness is greater than 2.0 μm, the running durability of the obtained tape can be unsatisfactory fail.

Possible and it is preferred that the above-mentioned coating layer C on the surface (page across from the magnetic layer side, when a magnetic tape of the polyester film to be prepared) on the above-mentioned polyester layer A formed polyester layer D to form.

The first base film according to the present Invention may according to commonly known methods and methods collected in the industry become.

For example is a polyester at a temperature of melting point (Tm) to (Tm + 70) ° C melted to an unstretched film having an intrinsic viscosity of 0.35 to form 0.9 dl / g, which is then 2.5 to 5.5 times in uniaxial Direction (longitudinal or transverse direction) at a temperature of (Tg-10) to (Tg + 70) ° C (Tg: glass transition temperature of the polyester) and then 2.5 to 5.5 times in one direction, perpendicular to the above-mentioned direction (transverse direction, if the film first in the longitudinal direction is stretched) at a temperature of (Tg) to (Tg + 70) ° C stretched is to produce a biaxially oriented film. In this Case is the area stretch ratio is preferred 9 to 25, more preferably 12 to 25. Orientation can either a simultaneous biaxial orientation or a sequential biaxial Be orientation.

Further For example, the above biaxially oriented film can be heated at a temperature of (Tg + 70) to (Tm) ° C heat-set become. For example, a polyethylene terephthalate film is preferred at 190 to 230 ° C heat set. The heat-setting time is e.g. 1 to 60 s.

to Production of a polyester film may contain additives by the above inert particles, e.g. stabilizers, Colorants and intrinsic viscosity modifiers for a molten polymer may be contained in the polyester as needed.

The from the polyester layer A and the polyester layer D existing laminate can according to commonly known Process and methods collected in the industry become. Of these, production by coextrusion is preferred.

To the Example will be in the case of a biaxially oriented polyester film a polyester (polyester A) which contains the above-mentioned inert particles A contains and a flat layer, and a polyester (polyester D), the contains the inert particles D. and forms a rough layer in a molten state in one extrusion die or in front of the nozzle (former is called "coextrusion system with separate feed channels "and the latter as a" manifold block system ") to each other laminated to produce a laminate structure having a suitable thickness ratio, which then out of the nozzle at a temperature of (Tm) to (Tm + 70) ° C in the form of a film coextruded and by cooling is solidified to produce an unstretched laminated film.

The formation of the coating layer B and the coating layer C on the polyester layer according to before lying invention can be carried out by the application of aqueous coating solutions.

The Coating will be on the surface the polyester layer is done, before that the final one Stretch is subjected, wherein the film is preferably in at least a uniaxial direction after coating is stretched. Of the Coating film is dried before or during stretching. The coating is preferably laminated to an unstretched Foil or one in the longitudinal direction (uniaxially) stretched laminated film carried out, preferably at a longitudinal direction (uniaxially) stretched laminated film. There are no special ones restrictions in terms of coating, however, find roll coating and die coating Use.

Of the Solids content of the above-mentioned coating solution, in particular an aqueous one Coating solution is preferably 0.2 to 8% by weight, more preferably 0.3 to 6% by weight, especially preferably 0.5 to 4 wt .-%. Other components, such as surfactants, stabilizers, Dispersants, UV absorbers and thickeners may be added the coating solution (preferably an aqueous Coating Solution) added be in the limits where the effect of the present invention is not prevented.

In the present invention, the longitudinal and transverse Young's moduli of the laminated film preferably become 450 kg / mm ² or more and 600 kg / mm ² or more, more preferably 480 kg / mm ² or more and 680 kg, respectively / mm ² or more, much more preferably 550 kg / mm ² or more or 800 kg / mm ² or more, particularly preferably 550 kg / mm ² or more or 1 000 kg / mm ² or more, adjusted to properties How to improve head contact and running durability of the obtained magnetic recording medium and reduce the thickness of the film.

The crystallinity the polyester layer is desirably 30 to 50% when the polyester is polyethylene terephthalate, and From 28 to 38% when the polyester is polyethylene-2,6-naphthalenedicarboxylate is. If the crystallinity falls below the lower limit, the heat shrinkage factor tends to become large, and if the crystallinity exceeds the upper limit, deteriorates the abrasion resistance of the film, which slightly a white one Powder is formed when the foil is in sliding contact with the surface of a Roll or a guide pin comes.

The first base film according to the present The invention may be embodied in a deposition type magnetic recording medium for recording high density with excellent electromagnetic conversion properties, e.g. Output in a short wavelength range, S / N and C / N, few drop-outs and small error rate by forming a ferromagnetic metal thin film layer of iron, cobalt, Chromium or an alloy substantially formed thereof or Oxide on the surface the polyester layer A (flat layer), preferably the coating layer B, by vacuum evaporation, sputtering, ion plating or the like, sequentially forming a diamond-like carbon protective layer (DLC) or the like and a fluorine-containing carboxylic acid-based Lubricant layer on the surface the Ferromagnetmetalldünnfilmlage after Need according to the purpose and use and further forming a Backsheet layer on the opposite of the ferromagnetic layer of the polyester layer A. Side, preferably the surface the coating layer C or the polyester layer D, as required a known method. This deposition type magnetic recording medium is extraordinary well suited as magnetic tape medium for Hi8 for recording analogue Signals and digital video cassette recorder (DVC), data 8 mm and DDSIV, for recording digital signals.

The first base film of the present invention can be further transformed into a metal-coated magnetic recording medium for high-density recording having excellent electromagnetic conversion characteristics, eg, output in a short wavelength region, S / N and C / N, few drop-outs and small error rate by applying a coating solution prepared by uniformly dispersing iron or needle-like fine magnetic powders (metal powders) containing iron as a main component in a binder such as polyvinyl chloride or vinyl chloride-vinyl acetate copolymer on the surface of the polyester layer A (flat layer), preferably the coating layer B. to form a magnetic layer having a thickness of 1 μm or less, preferably 0.1 to 1 μm, and further forming a backing layer on the opposite side of the magnetic layer of the polyester layer A, preferably on the surface of the coating layer C or the polyes D, as required by a known procedure. A non-magnetic layer may be formed on the surface of the polyester layer A, preferably the coating layer B, as a layer underlying the metal powder-containing magnetic layer as occasion demands by applying a coating solution prepared by dispersing fine particles of titanium oxide or the like which are present in the non-magnetic layer. magnetic layer are contained in the same organic binder as that of the magnetic layer. This metal-coated magnetic recording medium is exceptional Well suited as a tape medium for 8 mm video, Hi8, β-cam SP and W-VHS for recording analog signals and digital video cassette recorder (DVC), data 8 mm, DDSIV, digital β-cam, D2, D3 and SX, for Recording digital signals.

The first base film according to the present The invention may further be incorporated in an oxide-coated magnetic recording medium for recording high density with excellent electromagnetic conversion properties, e.g. Output in a short wavelength range, S / N and C / N, few drop-outs and small error rate by applying a coating solution prepared by uniform dispersion of needle-like fine magnetic powders such as iron oxide or chromium oxide, or lamellar fine magnetic powders, such as barium ferrite, in one Binder such as polyvinyl chloride or vinyl chloride-vinyl acetate copolymer, on the surface the polyester layer A (flat layer), preferably the coating layer B, a magnetic layer having a thickness of 1 μm or less, preferably 0.1 to 1 micron to form, and further forming a backsheet layer on the magnetic Location of the polyester layer A opposite Side, preferably the surface the coating layer C or the polyester layer D, as required a known method. A non-magnetic layer can be on the surface the polyester layer A, preferably the coating layer B, as a underlying the above-mentioned oxide powder-containing magnetic layer Layer can be formed as required by applying a coating solution prepared by dispersing fine titanium oxide particles or the like, which are contained in the non-magnetic layer, in the same organic binder such as the magnetic layer. This oxide-coated Magnetic recording medium is suitable as an oxide-coated magnetic recording medium for recording high density, e.g. Data streamer QIC for recording digital Signals.

at The present invention includes examples of the thermoplastic resins for forming the first thermoplastic layer (called "thermoplastic layer B" or "layer B") and the second thermoplastic layer (also "Thermoplastic layer A "or" layer A "called) polyester-based Resins, polyamide resins, polyimide resins, polyether-based resins, polycarbonate-based Resins, polyvinyl based resins and polyolefin based resins. Of these polyester-based resins are preferred and particularly preferred aromatic polyesters.

The thermoplastic resin for forming the first thermoplastic layer (in The following also called "Thermoplast B") and the thermoplastic resin for forming the second thermoplastic layer (in Following also "Thermoplastic A "called) can be varied be, are preferred but similar.

The The above-mentioned aromatic polyesters include polyethylene terephthalate, Polyethylene isophthalate, polytetramethylene terephthalate, poly-1,4-cyclohexylenedimethylene terephthalate and polyethylene-2,6-naphthalate (polyethylene-2,6-naphthalenedicarboxylate). Of these For example, polyethylene terephthalate and polyethylene-2,6-naphthalate are preferred.

Of the Polyester may be a homopolyester or copolyester. In the event of of a copolyester include examples of a comonomer for polyethylene terephthalate or polyethylene-2,6-naphthalate other diol components, such as diethylene glycol, Propylene glycol, tetramethylene glycol, hexamethylene glycol, neopentyl glycol, Polyethylene glycol, 1,4-cyclohexanedimethanol and p-xylylene glycol, other dicarboxylic acid components, like adipic acid, sebacic, phthalic acid, isophthalic acid, terephthalic acid (in the case of polyethylene-2,6-naphthalate), 2,6-naphthalene (in the case of polyethylene terephthalate) and 5-sodiosulfoisophthalic acid, and Oxycarboxylic components such as p-oxyethoxybenzoic acid. The amount of comonomer is 20 mol% or less, preferably 10 mol% or less, based on the entirety of all diol components in the case of a diol component or the totality of all dicarboxylic acids and oxycarboxylic acids in Case of a dicarboxylic acid component and an oxycarboxylic acid component.

Further can be a polyfunctional compound with a functionality of 3 or more, e.g. trimellitic or pyromellitic acid, be copolymerized. In this case, the connection can be in one be copolymerized in such amount that the polymer substantially is linear, e.g. 2 mol% or less.

Examples for a Comonomer for Polyester, which of polyethylene terephthalate and polyethylene-2,6-naphthalate are different, are the same as above.

The The above-mentioned polyesters are known per se and can after be prepared per se known methods.

The thermoplastic layer A contains third inert particles (hereinafter also referred to as "inert particles D") having an average particle diameter of the primary particles of 100 to 2,000 nm in an amount from 0.001 to 5% by weight, based on the layer A.

preferred examples for The inert particles D include fine particles of an inorganic one Compound, e.g. (1) heat-resistant polymer particles (Particles of cross-linked silicone resin, cross-linked polystyrene, cross-linked Acrylic resin, melamine-formaldehyde resin, aromatic polyamide resin, polyimide resin, Polyamideimide resin and crosslinked polyesters), (2) metal oxides (e.g. Aluminum sesquioxide, titania, silica, magnesia, Zinc oxide and zirconia), (3) metal carbonates (e.g., magnesium carbonate and calcium carbonate), (4) metal sulfates (e.g., calcium sulfate and Barium sulfate), (5) carbon (e.g., carbon black, graphite and diamond) and (6) clay minerals (such as kaolin, clay and bentonite). Of these are crosslinked silicone resin particles, crosslinked polystyrene resin particles, Melamine-formaldehyde resin particles, polyamide-imide resin particles and fine particles of aluminum sesquioxide (aluminum oxide), titanium dioxide, silicon dioxide, Zirconia, synthetic calcium carbonate, barium sulfate, diamond and kaolin preferred. More preferred are crosslinked silicone resin particles, crosslinked Polystyrene resin particles and fine particles of aluminum sesquioxide (Alumina), titanium dioxide, silica and calcium carbonate.

Of the average particle diameter (dD) of the primary particles the inert particle D is 100 to 2,000 nm, preferably 200 to 1,500 nm, more preferably 200 to 1 000 nm, more preferably 200 to 800 nm.

Of the Content of inert particles D is 0.001 to 5 wt .-%, preferably 0.01 to 4 wt .-%, more preferably 0.03 to 3 wt .-%, particularly preferably 0.05 to 2.0% by weight, based on the layer A.

If the average particle diameter of the primary particles the inert particle D is smaller than 100 nm or when its content is less than 0.001 wt .-%, based on the layer A, the winding properties and Antiblock properties unsatisfactory. If the average Particle diameter is greater than 2 000 nm or when the content is over 5 wt .-%, based on the position A, the surface of the falls Position B rough by the shape transmission the projections on the surface location B or from top to bottom of location B the projections, whereby the electromagnetic conversion characteristics deteriorate become.

The inert particles D can one type of particle or a mixture of two or more consist of different types of particles. When the inert particles D from a mixture of two or more different types of Particles can exist colloidal silica and fine particles such as alumina with an α, γ, δ or θ crystal form preferably as second and third particles (fine particles) with a smaller average particle diameter of the primary particles as the average particle diameter dD of the primary particles the above-mentioned inert particles D are used. From the above examples for the inert particles D having an average particle diameter dd can Further, fine particles having a small average particle diameter used as second and third particles (fine particles).

Of the average particle diameter of the fine particles is preferred 5 to 400 nm, more preferably 10 to 300 nm, particularly preferably 30 to 250 nm, and is preferably 50 nm or more, more preferably by 100 nm or more, more preferably by 150 nm or more smaller as the above-mentioned average particle diameter dD. Of the Total content of the second and third particles (fine particles) is preferred 0.005 to 1% by weight, more preferably 0.01 to 0.7% by weight, especially preferably 0.05 to 0.5 wt .-%, based on the layer A.

The Thermoplastic layer A contains an ester wax of an aliphatic monocarboxylic acid with 8 or more carbon atoms and a polyhydric alcohol in an amount from 0.001 to 10% by weight, based on the layer A.

The Number of carbon atoms of the above-mentioned aliphatic monocarboxylic acid is 8 or more, preferably 8 to 34. When the number of carbon atoms is less than 8 is falls the heat resistance of the obtained ester wax unsatisfactory, causing the aliphatic Monocarboxylic acid under the heating conditions for dispersing the ester wax in the thermoplastic A slightly decomposed becomes.

Examples of the aliphatic monocarboxylic acid having 8 or more carbon atoms include pelargonic acid, capric acid, undecynic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachic acid, behenic acid, lignoceric acid, cerotic acid, montanic acid, melissic acid, hentriacontanoic acid, petroselinic acid, oleic acid , Erucic acid, linoleic acid acid and acid mixtures containing them.

The Alcohol component of the ester wax according to the present invention a polyhydric alcohol having 2 or more hydroxyl groups. From the point of view the heat resistance For example, a polyhydric alcohol having 3 or more hydroxyl groups is preferred. When using a monoalcohol, the heat resistance of the ester wax formed falls unsatisfactory. Preferred examples of the polyhydric alcohol having 2 hydroxyl groups include Ethylene glycol, propylene glycol, trimethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, diethylene glycol, triethylene glycol and polyethylene glycol. examples for the polyhydric alcohol having 3 or more hydroxyl groups include glycerin, Erythritol, threitol, pentaerythritol, arbitol, xylitol, talitol, Sorbitol and mannitol.

The Ester wax, which from the above-mentioned aliphatic monocarboxylic acid and polyalcohol is a monoester, diester or triester, dependent on from the number of hydroxyl groups of the polyhydric alcohol. Under the Aspect of heat resistance a diester is more preferable than a monoester and a triester more preferred than a diester. Preferred examples of the ester wax include sorbitan tristearate, pentaerythritol tribehenate, glycerol tripalmitate and polyoxyethylene distearate.

The the aforesaid ester wax can be a partially hydrolyzed ester wax, consisting of an aliphatic monocarboxylic acid and a polyalcohol. The partially hydrolyzed ester wax is obtained by partial esterification a higher one fatty acid having 8 or more carbon atoms with a polyalcohol followed of saponifying the partially esterified product with a metal hydroxide with a valence of 2 or more. Examples of the partially hydrolyzed Ester wax includes wax E, wax OP, wax O, wax OM and wax FL (trade name of the company Hoechst AG), obtained by saponification a montanic acid diester with calcium hydroxide.

The above-mentioned ester waxes for themselves used alone or as a combination of two or more.

The Thermoplastic layer A contains the above-mentioned ester wax in an amount of 0.001 to 10% by weight, preferably 0.01 to 5 wt .-%, more preferably 0.05 to 2 wt .-%, especially preferably 0.1 to 1 wt .-%, based on the layer A.

If the content of ester wax in layer A is lower than 0.001% by weight, the blocking improving effect is not obtained. If the salary is higher than 10 wt%, becomes a big one Amount of a wax component due to emigration in the film manufacturing process on the opposite Transferred side of the rolled foil. This will cause the adhesion between a Metalldepositionslage and the base film adversely prevented.

Of the Water contact angle of the surface, not with the position B of the above-mentioned thermoplastic layer A in Contact stands, amounts 70 to 90 °, preferably 71 to 89 °, more preferably 72 to 88 °, more preferably 74 to 86 °. If the water contact angle is less than 70 °, the blocking improving Effect not received. When the water contact angle is larger as 90 °, it falls Coating in the step of applying a backsheet layer uneven.

The first thermoplastic layer (hereinafter also referred to as "thermoplastic layer B") exists on the magnetic layer side, when a magnetic tape is made from the polyester film of the present invention should be to the handling characteristics and the characteristic Properties of the magnetic tape in the manufacture or in the Improve processing of the film.

The surface roughness WRa of the thermoplastic layer B is 0.1 to 4 nm, preferably 0.2 to 3.5 nm, more preferably 0.3 to 3.0 nm, more preferably 0.4 to 2.5 nm. When the WRa value is smaller is 0.1 nm, film production becomes extremely difficult, and if the WRa value is greater than 4 nm, the electromagnetic conversion characteristics deteriorate.

These surface roughness (WRa) can be set via the particle diameter and / or the amount of in the thermoplastic layer B to be absorbed inert particles.

The Thermoplastic layer B may contain essentially no particles, or it may contain inert fine particles (hereinafter also referred to as "inert particles E").

When the thermoplastic layer B contains substantially no particles, a magnetic one becomes advantageous Received recording medium having excellent electromagnetic conversion properties.

Become the thermoplastic layer B particles are added in the limits in which no detrimental Influence is exerted on the electromagnetic conversion properties, the running durability is improved. More specifically, the inert particles E having a volume-forming coefficient of 0.1 to π / 6 and a average particle diameter of the primary particles from 30 to 400 nm are preferably in the thermoplastic layer B in an amount from 0.001 to 0.2% by weight.

preferred examples for the inert particles E include heat-resistant organic polymer fine particles, e.g. made of cross-linked silicone resin, cross-linked polystyrene, cross-linked Styrene-divinylbenzene copolymer, polymethyl methacrylate, methyl methacrylate copolymer, crosslinked methyl methacrylate copolymer, polytetrafluoroethylene, polyvinylidene fluoride, Polyacrylonitrile and benzoguanamine resin; and inorganic compounds such as Silica, alumina, titania, kaolin, talc, graphite, Calcium carbonate, feldspar, molybdenum disulfide, carbon black and Barium sulfate.

The inert particles E have a volume-forming coefficient (f) represented by the following equation (I) of 0.1 to π / 6, preferably 0.2 to π / 6, more preferably 0.4 to π / 6: f = V / R 3 (I) where f is a volume forming coefficient, where V is the volume (μm ³ ) of each particle, and R is the average particle diameter (μm) of the particles.

The Particles with a volume-forming coefficient (f) of π / 6 are globular (spherical). This means, the particles with a volume - forming coefficient (f) of 0.4 to π / 6 are in the Essentially globular, spherical or oval like a rugby ball and are preferred as inert particles E. The particles with a volume-forming coefficient (f) of less as 0.1, e.g. Flake-like particles worsen the running durability disadvantageous.

Of the average particle diameter dE of the inert particles E is 30 to 400 nm, preferably 40 to 200 nm, more preferably 50 to 100 nm. When the average particle diameter dE is smaller than 30 nm, the slipperiness can the resulting film unsatisfactory, and if the average Particle diameter dE is larger than 400 nm, can the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The inert particles E can one type of particle or a mixture of two or more consist of different types of particles.

If the inert particles E are contained in the thermoplastic layer B, is the content of inert particles E in the thermoplastic layer B 0.001 to 0.2% by weight, preferably 0.01 to 0.1% by weight, more preferably 0.02 to 0.05% by weight based on the layer B. When the content is lower as 0.001 wt%, the slipperiness of the obtained film may be unsatisfactory fail, and if the salary higher is 0.2 wt .-%, the electromagnetic conversion properties of the obtained magnetic Recording medium unsatisfactory.

If the first coating layer, which 0.5 to 30 wt .-% of the second inert fine particles (hereinafter also referred to as "inert particles B") with an average Particle diameter of 10 to 50 nm and a volume-forming coefficient from 0.1 to π / 6 contains on that surface is formed, which does not interfere with the thermoplastic layer A of the thermoplastic layer B is in contact, is advantageously a metal deposition magnetic recording medium obtained with excellent running durability.

The Resin for forming the first coating layer is preferably an aqueous one aqueous Polyester resin, aqueous Acrylic resin or aqueous Polyurethane resin, more preferably an aqueous polyester resin.

Examples of the aqueous polyester resin include polyester resins each composed of at least one polycarboxylic acid such as isophthalic acid, phthalic acid, 1,4-cyclohexanedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, sodium 5-sulfoisophthalate, potassium 2-sulfoterephthalate, trimellitic acid, trimesic acid, monopotassium salt of trimellitic acid or p-hydroxybenzoic acid, as the acid component and at least one polyhydroxy compound, such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, p-xylylene glycol, dimethylolpropane or bisphenol A adduct with ethylene oxide, as glycol com component; Graft polymers and block copolymers prepared by bonding an acrylic polymer chain to a polyester chain; and acrylic-modified polyester resins comprising two different polymers which form a specific physical structure in the microparticle (type IPN (interpenetrating polymer network) or type core-shell). The aqueous polyester resin may be of any type that is soluble, emulsifiable or finely dispersible in water. A sulfonate group, carboxylate group or polyether unit may be introduced into the molecule of the polyester resin to provide a hydrophilic nature.

The are inert particles B contained in the first coating layer preferably inert particles which are present in a coating solution only settle hard and have a relatively low relative density. Preferred examples of the inert particles B include heat-resistant polymer particles, e.g. cross-linked silicone resin, cross-linked acrylic resin, cross-linked polystyrene, Melamine-formaldehyde resin, aromatic polyamide resin, polyamide-imide resin, crosslinked polyesters and wholly aromatic polyesters, silica (Silica) and calcium carbonate. Particularly preferred are crosslinked Silicone resin particles, silica particles and organic particles of the core-shell type (Core: cross-linked polystyrene, shell: Polymethyl methacrylate).

Of the average particle diameter dB of the primary particles the inert particle B is 10 to 50 nm, preferably 15 to 45 nm, more preferably 18 to 40 nm. When the average particle diameter dB is smaller than 10 nm, the slipperiness can the resulting film unsatisfactory, and if the average Particle diameter dB is greater than 50 nm the electromagnetic conversion properties of the obtained magnetic recording medium unsatisfactory.

The inert particles B have a volume-forming coefficient (f) represented by the above-mentioned equation (I), from 0.1 to π / 6 0.2 to π / 6, more preferably 0.4 to π / 6 on. The particles with a volume-forming coefficient (f) of less as 0.1, e.g. flake-like particles, make it difficult, a satisfactory To maintain maturity.

Of the Content of inert particles B is 0.5 to 30% by weight, preferably 2 to 20 wt .-%, more preferably 3 to 10 wt .-%, based on the Solids content of the first coating layer. If the salary is lower is more than 0.5% by weight, the slipperiness of the resulting film may be unsatisfactory fail, and if the salary higher is than 30 wt .-%, can the electromagnetic conversion characteristics of the obtained magnetic Recording medium unsatisfactory.

The Total thickness of the laminated thermoplastic film containing the base film according to the present Invention is generally 2.5 to 20 μm, preferably 3.0 to 10 μm, more preferably 4.0 to 10 μm. The thickness of the thermoplastic layer A is preferably 1/2 or less, more preferably 1/3 or less, more preferably 1/4 or less the total thickness of the laminated thermoplastic film. The thickness of the Thermoplastic layer B is preferably 1/2 or more, more preferably 2/3 or more, more preferably 3/4 or more of the total thickness of laminated thermoplastic film. The thickness of the coating layer C is generally 1 to 100 nm, preferably 2 to 50 nm, more preferably 3 to 10 nm, more preferably 3 to 8 nm.

The laminated thermoplastic film according to the present Invention may according to commonly known methods and methods collected in the industry become. Of these, the from the thermoplastic layer A and the thermoplastic layer B existing laminate structure preferably prepared by coextrusion and the first coating layer is preferably by coating educated.

For example, in the case of a biaxially oriented polyester film, the thermoplastic A containing the above-mentioned inert particles D and the ester wax finely dispersed therein and the thermoplastic B containing the inert particles E as required are filtered with high accuracy and melted in the molten state an extrusion die or before the die (the former is referred to as a "split feed channel coextrusion system" and the latter as a "manifold block system") to produce a laminate structure of the above preferred thickness ratio which is then removed from the die at a melting point (Tm) temperature. bis (Tm + 70) ° C is coextruded into the form of a film and solidified by cooling with a chill roll at 40 to 90 ° C to prepare an unstretched laminated film. Then, the above unstretched laminated film is set at 2.5 to 8.0 times, preferably 3.0 to 7.5 times, in the uniaxial direction (longitudinal or transverse direction) at a temperature of (Tg-10) to ( Tg + 70) ° C (Tg: glass transition temperature of the polyester) and then to 2.5 to 8.0 times, preferably 3.0 to 7.5 times in a direction perpendicular to the above-mentioned direction (transverse direction, when the film is first stretched in the longitudinal direction) is stretched at a temperature of (Tg) to (Tg + 70) ° C according to a generally conventional method. The film can be further stretched in the longitudinal and / or transverse direction as needed. That is, a two-level, three-level, four-level or multi-level orientation can be performed. The total draw ratio is generally 9, preferably 12 to 35, more preferably 15 to 30.

Further becomes the above-mentioned biaxially oriented film for the purpose of crystallization heat-set at a temperature of (Tg + 70) to (Tm-10) ° C, e.g. 180 up to 250 ° C in the case of a polyethylene terephthalate film, to be excellent dimensional stability provide. The heat-setting time is preferably 1 to 60 s.

to Production of a laminated thermoplastic film may include additives used by the above inert particles, e.g. stabilizers, Colorants and intrinsic viscosity modifiers for a molten polymer, as required in thermoplastics A and B be included.

The Forming the first coating layer on the thermoplastic layer B according to the present Invention can be carried out be by the application of an aqueous coating solution.

The Coating is on the surface the thermoplastic layer B performed, before that the final one Stretch is subjected, wherein the film is preferably in at least a uniaxial direction after coating is stretched. Of the Coating film is dried before or during stretching. The Coating is preferred on an unstretched laminated film or one in the longitudinal direction (uniaxially) stretched laminated film carried out, preferably at a longitudinal direction (uniaxially) stretched laminated film. There are no special ones restrictions in terms of coating, however, find roll coating and die coating Use.

Of the Solids content of the above-mentioned coating solution, in particular the aqueous Coating solution is preferably 0.2 to 8% by weight, more preferably 0.3 to 6% by weight, especially preferably 0.5 to 4 wt .-%. Other components, such as surfactants, stabilizers, Dispersants, UV absorbers and thickeners may be added the coating solution (preferably an aqueous Coating Solution) to be added in the limits where the effect of the present invention is not is prevented.

In the present invention, in order to obtain a thin magnetic recording medium having improved properties such as head contact and running durability, the longitudinal and transverse Young's moduli of the laminated film generally become 450 kg / mm ² or more and 600 kg / mm ^2, respectively or more, preferably 480 kg / mm ² or more or 680 kg / mm ² or more, more preferably 550 kg / mm ² or more or 800 kg / mm ² or more, particularly preferably 550 kg / mm ² or more or more 1 000 kg / mm ² or more.

The crystallinity the thermoplastic A and B is desirably 30 to 50% if the thermoplastics are polyethylene terephthalate, and 28 to 38% when the thermoplastics are polyethylene-2,6-naphthalate. Below the lower limit, the heat shrinkage factor of the film becomes large, and above the upper limit, the abrasion resistance deteriorates the film and it is easy to form a white powder on contact with the surface a roll or a guide pin.

According to the present The invention further provides: a magnetic recording medium comprising a laminated thermoplastic film comprising the above-mentioned thermoplastic sheet A and the above-mentioned thermoplastic sheet B formed on one side the thermoplastic sheet B, as a base sheet and a magnetic recording medium, comprising a laminated thermoplastic film comprising the above-mentioned thermoplastic layers A and B and a first coating layer formed on one Side not with the thermoplastic layer A of the thermoplastic layer B in contact, as a base film.

From a magnetic recording medium which is preferred a base film comprising a laminated thermoplastic base film as a base film according to the present Invention, and the above-mentioned first coating layer, which on that surface the first thermoplastic layer is formed, not with the second Thermoplastic layer of the base film is in contact, and a magnetic layer, which formed on the first coating layer of the base film is.

It It is understood that a description of the reference base film (the Reference Examples 1 to 6) to the process for producing a magnetic recording medium of the base film of the present invention Invention and application, the magnetic layer used, etc. of the magnetic recording medium directly or with those skilled in the art obvious modifications applies.

Examples

The The following examples are intended to explain the present invention in more detail; she but are in no way to be understood as limiting. "Parts" and "%" in the examples and comparative examples mean "parts by weight" or "weight percent" unless otherwise stated is specified. For The present invention has been the physical property values and characteristic properties according to the following methods measured and defined.

(1) intrinsic viscosity

These was measured from a solution in an orthochlorophenol solvent at 35 ° C Value received.

(2) Average Particle diameter (I) of the particles (average particle diameter: 60 nm or more)

This was measured by the CP-50 Centrifugal Particle Size Analyzer Shimadzu Corporation. The "equivalent Ball diameter "the to 50 percent by mass equivalent Particle was read from the cumulative curve of the particle diameter and the amount of particles of any size calculated from the obtained Centrifugal sedimentation curve, and as the average particle diameter (nm) taken ("Ryudo Sokutei Gijutsu ", released by Nikkan Kogyo Shimbunsha., pp. 242-247, 1975).

(3) Average Particle diameter of the particles (II) (average particle diameter: smaller than 60 nm)

particle with an average particle diameter of less than 60 nm, the small projections were measured by the light scattering method. That is, the "equivalent ball diameter" of the particles that 50% of the totality of all particles, obtained with the Nicomp Model 270 Submicron Particle Sizer (trade name) from Nicomp Instruments Inc., was called the average particle diameter (nm) taken.

(4) Volume shape coefficient (F)

From each particle, a scanning electron microscopic photograph was taken with a magnification corresponding to the size of the particle, and the maximum diameter (D) (μm) of the projection plane and the volume (V) (μm ³ ) of the particle were calculated using the Luzex 500 image analyzer Nippon Regulator Co., Ltd. was used to obtain a volume-forming coefficient according to the following equation (II). f = V / D 3 (II)

(5) density of the protrusions the surface and particle agglomeration rate

(a) base film

The density of the projections derived from inert fine particles on the surface of the base film was measured by a scanning electron microscope. Twenty different photographs of the surface of the base film were taken with a magnification of 5,000 times and at an angle of 45 ° to the surface in a statistically distributed manner. In the photographs, a protrusion formed by the agglomeration of two or more particles was referred to as an "agglomeration protrusion," unlike an "independent protrusion" formed by a single particle. The "agglomeration protrusions" and the "independent protrusions" in the above-mentioned surface photographs were counted to obtain the total number of "agglomeration protrusions" and "independent protrusions" per mm ² as the density of protrusions on the surface.

The agglomeration rate of the inert fine particles on the surface of the base film is defined by the following equation (III). Particle agglomeration rate (%) = [number of agglomeration protrusions] / (number of agglomeration protrusions + number of independent protrusions)] × 100 (III)

(b) Coating layer

The Density of the projections derived from inert fine particles the surface The coating layer was measured in the same manner as for the above Measurement (a) of the base film described except that 30 surface photographs by scanning electron microscope from the top right with 35,000 times Enlargement statistically distributed.

(6) thickness of each Layers of the laminated film and total thickness of the film

The total thickness of the film was measured by micrometer at 10 randomly distributed points and the mean of the measured data was used. With respect to the thickness of the individual layers, the thickness of a thin layer was measured by the following method, and the thickness of a thick layer was obtained by subtracting the thickness of the thin layer and the thickness of the coating layer from the total thickness of the film. That is, using a secondary ion mass spectrometer (SIMS), the concentration ratio (M ⁺ / C ⁺ ) of a metal element (M ⁺ ) derived from the highest concentration particles of the particles contained in the film became a range from the surface layer to the depth of 5,000 nm except for the coating layer, to which hydrocarbon (C ⁺ ) of the thermoplastic (polyester) was taken as the particle concentration, and the area from the surface to a depth of 5,000 nm was analyzed in the thickness direction. The particle concentration of the surface layer was low because the surface was a transition zone but became higher with increasing distance from the surface. In the present invention, after reaching a stable value of 1, the particle concentration became a stable value of 2 or simply decreased. Based on this distribution curve, a depth in which the particle concentration became (stable value 1 + stable value 2) / 2 became, in the former case, and a depth in which the particle concentration became (stable value 1) / 2 (this value) greater than the depth giving a stable value of 1), in the latter case taken as the thickness (μm) of the thin layer.

The Measurement conditions were as follows.

(a) measuring equipment

• Secondary ion mass spectrometer (SIMS): 6300 from Perkin Elmer Inc.

(b) measurement conditions

• Type of primary ions: O ²⁺
• Primary ion acceleration voltage: 12 kV
• Primary ion current: 200 nA
• Illuminated area: 400 μm
• Analysis area: 30% of the outlet
• Measurement vacuum degree: 6.0 × 10 ^-9 Torr
• E-GUNN: 0.5 KV - 3.0 A

If the particles that predominantly in an area of the surface layer are contained to a depth of 5,000 nm, organic polymer particles which are different from silicone resin, it is difficult to measure them with SIMS. Therefore, a concentration distribution curve became similar to above curve by FT-IR (Fourier transform infrared spectrometry) or XPS (photoelectron spectroscopy with x-ray excitation) measured particle-dependent, the surface etched was added to the thickness (μm) to get every layer.

(7) Thickness of coating layer

One small piece Film was fixed by means of epoxy resin and an ultrathin piece with a Thickness of approx. 600 Å by means of of a microtome (section in one direction parallel to the direction of the film). This sample was analyzed by a transmission electron microscope observed (H-800 Hitachi, Ltd.), and the interface of Coating layer was localized to the thickness (nm) of the coating layer to obtain.

(8) contact angle

This was measured with the contact angle measuring instrument of Kyowa Chemical Co., Ltd. measured. The film sample was allowed to stand at a temperature of 25 ° C and a humidity of 50% for 24 hours, 5 mg of distilled water was dropped on the film, and a photograph of the film sample taken from a horizontal direction after 20 seconds. The angle formed between the film and the tangent of the water droplet in the direction of the water droplet was taken as the contact angle (°).

(9) Film surface roughness (Ra)

• (a) Radius des Tasterendes: 2 μm
• (b) Messdruck: 30 mg
• (c) Cut-off: 0,08 mm
• (d) Messlänge: 1,0 mm
• (e) Datenkompilation: Die Oberflächenrauheit derselben Probe wurde fünfmal gemessen, der größte Wert wurde ausgeschlossen und der Mittelwert der vier anderen Daten durch Runden auf vier Dezimalstellen erhalten.

The surface roughness (Ra) is a value defined as arithmetic mean roughness (Ra) by JIS-B0601, and was evaluated for the present invention with the button surface roughness meter (Surfcorder SE-30C) manufactured by Kosaka Kenkyusho Co., Ltd. measured. The measurement conditions were as follows.

• (a) radius of the probe end: 2 μm
• (b) Measurement pressure: 30 mg
• (c) cut-off: 0.08 mm
• (d) Measuring length: 1.0 mm
• (e) Data Compilation: The surface roughness of the same sample was measured five times, the largest value was excluded and the average of the four other data was obtained by rounding to four decimal places.

(10) Arithmetic mean roughness (Surface roughness) (WRa)

Using the contactless 3-D roughness meter under the trade name TOPO-3D of WYKO Co., Ltd. For example, the surface roughness was measured under the conditions of measurement area 242 μm × 239 μm (0.058 mm ² ) and 40 times the measurement magnification to obtain the surface roughness profile (original data). The center-line arithmetic mean (WRa) defined by the following equations (IV) and (V) was obtained by surface analysis based on software included in the above roughness meter.

ZJK is a height on a 3-D roughness diagram in a j-th position and a k th position in a measuring direction (242 μm) and one direction vertical to the measuring direction (239 μm), when these directions are divided into M and N sections, respectively.

(11) Young's modulus

A sample film having a length of 300 mm and a width of 12.7 mm was used with the Tensilon Tensile Tester from Toyo Baldwin Co., Ltd. at a strain rate of 10% / min in a space maintained at a temperature of 20 ° C and a humidity of 50%, and the Young's modulus was calculated from the following equation (VI) using the first linear part of a tensile stress Strain curve calculates: E = Δσ / Δε (VI) where E is a Young's modulus (kg / (mm ² ), where Δσ is a voltage difference between two points on a straight line caused by the original average cross-sectional area, and where Δε is a strain difference between the above two points.

(12) blocking peel force of second base film

The second thermoplastic layer of a film sample obtained from a rolled film having a length of 100 mm and a width of 200 mm was subjected to corona treatment at a room temperature of 20 ± 2 ° C and a humidity of 40 ± 5%.

The above-mentioned corona treatment was carried out with the high frequency power supply "CG-102" (trade name) of the company Kasuga Denki Kabushiki Kaisha under the following conditions.
Electricity: 4.5 A
Electrode distance: 1.0 mm
Treatment time: Treatment at a speed of 1.2 m / min by passage between the electrodes.

The treated side of the film was brought into contact with the side opposite the second thermoplastic layer of the film and aged at a pressure of 100 kg / cm ² , a temperature of 60 ° C and a humidity of 80% for 17 hours, and the peel force per 100 mm width of the film was obtained by means of the above tensile tester "Tensilon" (trade name).

(13) Winding properties

⌾;

28 oder mehr akzeptierte Rollen

O;

25 bis 27 akzeptierte Rollen

X;

16 bis 24 akzeptierte Rollen

XX;

15 oder weniger akzeptierte Rollen

After the winding conditions were optimized at the time of slitting, 30 rolls of 600 mm wide and 12,000 m long strips were cut at a speed of 100 m / min, and rolls without soiling, protrusions and wrinkles on the surface of the film accepted after slitting. The winding properties of the rolls were evaluated based on the following criteria.

⌾;

28 or more accepted roles

O;

25 to 27 accepted roles

X;

16 to 24 accepted roles

XX;

15 or less accepted roles

(14) Applicability (workability) the backsheet

O;

keine Beschichtungsungleichförmigkeiten und Abstoßung bei der Rückschichtlage beobachtet

X;

Beschichtungsungleichförmigkeiten oder Abstoßung bei der Rückschichtlage beobachtet

In the production process for a magnetic tape, the surface of the second thermoplastic layer after application of a back layer was visually observed and evaluated based on the following criteria.

O;

no coating nonuniformities and repulsion observed in the backsheet layer

X;

Coating nonuniformity or repulsion observed in the backsheet layer

(15) Magnetic tape production and evaluation of the characteristics

Two ferromagnetic thin film layers of 100% cobalt were formed on the flat surface of the film of the present invention to obtain a thickness of 0.2 μm (about 0.1 μm per layer) by vacuum evaporation. Further, a diamond-like carbon (DLC) film and a fluorine-containing carboxylic acid-based lubricant layer were sequentially formed on the surface of the layers, and a back layer layer was formed on the side opposite to the ferromagnetic thin film layer side of the film by a known method. Then, the obtained laminated film was slit to a width of 8 mm and loaded in a commercially available 8 mm video cassette. Then, the characteristic properties of the obtained tape were measured using the following commercially available equipment.
8 mm video tape recorder: EDV-6 000 from Sony Corporation
C / N Measurement: Noise Meter of Shibasoku Co., Ltd.

(a) C / N measurement (electromagnetic Conversion properties)

One Signal with a recording wavelength of 0.5 μm (frequency about 7.4 MHz) was recorded and the ratio of 6.4 MHz and 7.4 MHz playback signals hereof taken as the C / N value of the tape, expressed as relative value to the C / N value of a commercially available 8 mm videotape of the deposition type assumed to be 0 dB.

(b) running time

⌾:

mehr als +0,0 dB Abweichung vom Referenzwert

O;

–1,5 bis 0,0 dB Abweichung vom Referenzwert

X;

weniger als –1,5 dB Abweichung vom Referenzwert

After recording and reproduction were repeated 1,000 times at a temperature of 40 ° C, a humidity of 80%, and a tape running speed of 85 cm / min., The C / N value became measured and the deviation from the initial value on the basis of the following criteria.

⌾:

more than +0.0 dB deviation from the reference value

O;

-1.5 to 0.0 dB deviation from the reference value

X;

less than -1.5 dB deviation from the reference value

(16) Measurement of the pH

Of the pH at a solvent temperature from 25 ° C was measured using the pH meter F-14 Horiba Co., Ltd. measured.

The Reference examples 1 to 6 are for information only and constitute not part of the invention.

Reference Example 1

100 Parts dimethyl terephthalate, 70 parts ethylene glycol, 35 mmol% calcium acetate, based on dimethyl terephthalate, and 35 mmol% magnesium acetate, based on the above standard, were combined, to perform a transesterification reaction according to a conventional method; trimethyl was in an amount of 40 mmol%, based on dimethyl terephthalate, added to terminate the transesterification reaction. An ethylene glycol slurry containing globular Silica with an average particle diameter of 45 nm and a pH of 9 as the first inert fine particles (inert Particle A), was immediately after completion of the transesterification reaction so that guaranteed was that the content of globular Silica was obtained in the polymer to 0.03%. Then it became Titanium trimellitate in an amount of 2 mmol%, based on dimethyl terephthalate, was added, and the resulting mixture was transferred to a polymerization vessel to a polycondensation reaction under a high vacuum of 26.7 Pa or less according to a usual Procedure by raising the temperature to 290 ° C to perform polyethylene terephthalate with an intrinsic viscosity of 0.60.

One Pellet of the obtained polyethylene terephthalate was heated at 170 ° C for 3 hours dried, transferred to the funnel of an extruder, melted at 300 ° C, through a copper wire filter with an average opening of 11 μm with greater Accuracy filtered, extruded through a slot die, a surface treatment subjected to about 0.3 S with a linear electrode and through Contact with a rotating cooling drum with a surface temperature from 20 ° C solidified to a 89 microns to obtain thick unstretched film.

The The unstretched film obtained was preheated to 3.3 times between Low-speed and high-speed rollers at one Foil temperature of 100 ° C stretched and cooled, and watery solutions with the following compositions (total solids content 1.0%) were on the front and back this in the longitudinal direction Stretched film applied by kiss coating.

(a) front side (first Coating layer)

• Binder: Acrylic modified polyester (IN-170-6 of the company Takamatsu Yushi Co., Ltd.); 68 parts (based on the solids content)
• Second inert fine particles (inert particles B): core-shell filler (Core: cross-linked polystyrene, shell: Polymethylmethacrylate) (average particle diameter 30 nm) (volume-forming coefficient 0.47) (SX8721 (D) -12 of JSR Corporation); 5 parts
• Surfactant X: (Nonion NS-208.5 from NOF Corporation); Part 1
• Surfactant Y: (Nonion NS-240 from NOF Corporation); 26 parts
• Thickness (after drying): 4 nm

(b) back side (second coating layer)

• Copolyester (terephthalic acid / isophthalic acid / 5-sodiosulfoisophthalic acid / ethylene glycol / bisphenol A adduct with 2 moles of propionic oxide = 97/1/2/60/40); 60 parts
• Inert Particles C: silica particles (average Particle diameter 60 nm); 10 parts
• hydroxypropyl methylcellulose; 20 parts of surfactant X: (Nonion NS-208.5 the company NOF Corporation); 10 parts
• Thickness (after drying): 15 nm

Subsequently, the stretched film was fed to a tenter to be 4.2 times in Transversely stretched at 120 ° C. The obtained biaxially oriented film was heat-set with 220 ° C hot air for 4 seconds to obtain a polyester film having a total thickness of 6.4 μm. The density of the projections derived from the inert particles A on the surface of the film was 42,000 / mm ² , and the agglomeration rate of the inert particles A was 15%. The biaxially oriented film had a surface roughness (Ra) of the front side (first coating layer) of 0.7 nm, a surface roughness of the back side (second coating layer) of 6 nm, a longitudinal Young's modulus of 500 kg / mm ² , a Young transverse modulus of 700 kg / mm ² and a density of the projections derived from the inert particles B on the surface of the front surface (first coating layer) of 11,000,000 / mm ² . Further characteristic properties of this film and the characteristics of a ferromagnetic thin film deposition magnetic tape obtained from this film are shown in Reference Table 2. In the production of the ferromagnetic thin film deposition magnetic tape, the flat surface (first coating layer) was a deposition surface.

Reference examples 2 and 4

polyester films were obtained in the same manner as in Reference Example 1, except that kind, average particle diameter and amount of inert Particle A changed were shown as in reference table 1. The in reference example 2 of polyester film obtained showed a surface roughness (Ra) of the front side of 0.8 nm and a surface roughness the back of 6.5 nm, and the obtained polyester film in Reference Example 4 showed a surface roughness the front of 1.0 nm and a surface roughness of the back of 6.7 nm. The characteristic properties of the obtained Films and ferromagnetic thin film deposition magnetic tapes obtained from the films are shown in reference table 2.

Reference Example 3

dimethyl terephthalate and ethylene glycol with the addition of manganese acetate as the transesterification catalyst, Antimony trioxide as a polymerization catalyst and phosphoric acid as Stabilizer after a usual Process polymerized. Silicone particles with an average Particle diameter of 0.7 μm and θ-alumina particles having an average particle diameter of 0.2 μm as third inert fine particles (inert particles D) added, so that ensures was that the final particle contents in the polymer to 0.05% or 0.3% were obtained. Polyethylene terephthalate (PET) (Resin D1) for the second polyester layer with an intrinsic viscosity of 0.60 was obtained by polymerization.

The Polyethylene terephthalate used in Reference Example 1 (hereinafter as "resin A1") and Resin D1 was at 170 ° C for 3 hours dried, fed to two extruders, at 300 ° C melted and by means of a Koextrusionsdüse with separate feed channels so laminated to each other so that the resin D1 layer on one side of the Resin A1 layer formed and cooled was to a 89 microns to obtain thick unstretched laminated film.

The obtained unstretched film was preheated, stretched to 3.3 times between low-speed and high-speed rolls at a film temperature of 100 ° C, and cooled, and the coating solution used in Reference Example 1 for the front side was coated on the front side (side of the resin -A1 layer) of the longitudinally stretched film to form a first coating layer. Subsequently, the stretched film was fed to a tenter to obtain a laminated polyester film having a total thickness of 6.4 μm in the same manner as in Reference Example 1. The obtained film had a surface roughness (Ra) of the front side (first coating layer) of 1.7 nm and a surface roughness of the back side (resin D1 layer side) of 7.8 nm, a Young's modulus in the longitudinal direction of 500 kg / mm ² and a transverse Young's modulus of 700 kg / mm ² . The thickness of the resin D1 layer was 0.9 μm. The characteristic properties of the obtained film and a ferromagnetic thin film deposition magnetic tape obtained from the film are shown in Reference Table 2.

Reference Examples 5 and 6

Polyethylene-2,6-naphthalate (Polyethylene-2,6-naphthalenedicarboxylate) (PEN) (Resin A2, Resin D2) to form two layers was obtained in the same way as in the polyester production process of Reference Example 1 except that kind, average particle diameter and amount of inert Particle A changed were as shown in reference table 1 and that the equimolar Amount of dimethyl-2,6-naphthalenedicarboxylate in place of the dimethyl terephthalate has been used.

The Resins A2 and D2 obtained were dried at 170 ° C for 6 hours, and the thickness of each layer was adjusted in the same way as in Reference Example 3, to an unstretched laminated film consisting of the resin A2 layer and the resin D2 layer. The obtained unstretched film was preheated, to 3.6 times between low-speed and high-speed rollers stretched and cooled at a film temperature of 135 ° C, and aqueous solutions with the following compositions were applied to the front (page the resin A2 layer) and back side (Side of the resin D2 layer) of the longitudinally stretched film applied in the same manner as in Reference Example 1 to a to form the first coating layer and a second coating layer.

(a) front side (first Coating layer)

• Binder: Acrylic modified polyester (IN-170-6 of the company Takamatsu Yushi Co., Ltd.); 63 parts (based on the solids content)
• Inert Particles B): acrylic filler (average particle diameter 25 nm) (volume-forming coefficient 0.42) (MA02W from Nippon Shokubai Co., Ltd.); 6.5 parts
• Surfactant X: (Nonion NS-208.5 from NOF Corporation); 0.5 parts
• Surfactant Y: (Nonion NS-270 from NOF Corporation); 20 parts
• Thickness (after drying): 6 nm

(b) back side (second coating layer)

• Acrylic modified polyester (SH551BK from Takamatsu Yushi Co., Ltd.); 50 parts
• Fourth inert fine particles (Particle C): Acrylic resin filler (average particle diameter 40 nm) (ME-6U of the company Nippon Shokubai Co., Ltd.); 15 parts
• hydroxypropyl methylcellulose; 15 parts
• Surfactant X: (Nonion NS-208.5 from NOF Corporation); 10 parts
• Siloxane copolymerized acrylic (X22-8053 from Shin-Etsu Chemical Co., Ltd.); 10 parts
• Thickness (after drying): 20 nm

Thereafter, the film was fed to a tenter to be stretched 4.9 times in the transverse direction at 150 ° C and heat set and further stretched 1.12 times in the transverse direction at 200 ° C to obtain a biaxially oriented film having a total thickness of 4 To obtain 4 μm. This film had a surface roughness (Ra) of the front side (first coating layer) of 0.6 nm and a surface roughness of the back side (second coating layer) of 6.2 nm in Reference Example 5, a surface roughness of the front side (first coating layer) of 0.5 nm and a surface roughness of the back surface (second coating layer) of 6.2 nm in Reference Example 6, a Young's modulus in the longitudinal direction of 560 kg / mm ² , a Young's modulus in the transverse direction of 1100 kg / mm ² , a density of protrusions derived from the inert particles B on the surface of the front side (first coating layer) of 10 500 000 / mm ² in Reference Example 5 and of 10 5 000 000 / mm ² in Reference Example 6. Other characteristics of these films and the characteristics of ferromagnetic thin film deposition magnetic tapes obtained from these films are shown in Table 2 of Reference.

Comparative Example 1

A Polyester film was obtained in the same manner as in Example 1, except that the inert particles A were not added. This film had a surface roughness (Ra) of the front side (first coating layer) of 0.6 nm and a surface roughness the back (second coating layer) of 6.2 nm. Further characteristic Properties of this film and the characteristics a Ferromagnetdünnfilmdepositions magnetic tape obtained from this film are shown in Table 4. The magnetic tape obtained from this film was inferior in terms of running time.

Comparative Example 2

A Polyester film was obtained in the same manner as in Example 2, except that the pH of the ethylene glycol slurry of changed inert particles A in 7 and that the amount of trimethyl phosphate was changed to 15 mmol%. The characteristic properties of this film and the characteristic Properties of a ferromagnetic thin film deposition magnetic tape obtained from this film are shown in Table 4. The magnetic tape obtained from this film was inferior in terms of running time.

Comparative Example 3

A Polyester film was obtained in the same manner as in Example 5, except that species, average particle diameter and amount of the inert particles A were changed as shown in Table 3 and that the pH the ethylene glycol slurry of the inert particles A in FIG. 12 has been. The characteristic features of this film and the characteristic properties of a product obtained from this film Ferromagnetic thin film deposited magnetic tape are shown in Table 4. The agglomeration rate of the inert particles A of this film was extraordinary high, and the magnetic tape obtained from this film was inferior to its electromagnetic conversion properties.

Comparative Example 4

A Polyester film was obtained in the same manner as in Example 5, except that species, average particle diameter and amount of the inert particles A were changed as shown in Table 3 shown. The characteristic features of this film and the characteristic properties of a product obtained from this film Ferromagnetic thin film deposited magnetic tape are shown in Table 4. The resulting film showed a high Density of protrusions, and the magnetic tape obtained from this film was in terms of his inferior to electromagnetic conversion properties.

As from Tables 1 to 4, the have from the Films according to the present Invention obtained magnetic tapes excellent electromagnetic conversion properties and running durability on, while the magnetic tapes, those from the outside obtained in the scope of the present invention be inferior in terms of the above properties are.

In Tables 1 and 3 and in Reference Table 1 are * 1) PET for polyethylene terephthalate and PEN for Polyethylene-2,6-naphthalate (polyethylene-2,6-naphthalenedicarboxylate).

It Now follow Examples 1 to 6 and Comparative Examples 1 to 5 of the base film according to the present Invention. The inert particles D, E and the ester wax, which be used in these examples and comparative examples are given below.

The following substances were used as inert particles D.
Spherical silica; average particle diameter 600 nm
Globular silica; average particle diameter 400 nm
θ-alumina; average particle diameter 60 nm
silicone; average particle diameter 500 nm
Crosslinked polystyrene; average particle diameter 800 nm
Vaterite crystal-based calcium carbonate; average particle diameter 200 nm

The following substances were used as inert particles E.
Spherical silica; average particle diameter 200 nm (volume-forming coefficient 0.5)
Globular silica; average particle diameter 60 nm (volume-forming coefficient 0.5)

• (a-1) Sorbitantristearat (Schmelzpunkt 55°C)
• (a-2) Produkt, erhalten durch Verseifung eines Montansäurediolesters mit Calciumhydroxid, "Wachs E" (Handelsname) der Firma Hoechst AG (Schmelzpunkt 86°C)
• (a-3) Glycerintripalmitat
• (a-4) Produkt, erhalten durch Verseifung eines Montsäurediolesters mit Calciumhydroxid, "Wachs OP" (Handelsname) der Firma Hoechst AG (Schmelzpunkt 81°C)
• (a-5) Pentaerythritoltribehenat

The following substances were used as ester wax.

• (a-1) sorbitan tristearate (melting point 55 ° C)
• (a-2) Product obtained by saponifying a montanic acid diol ester with calcium hydroxide, "Wachs E" (trade name) of Hoechst AG (melting point 86 ° C)
• (a-3) glycerol tripalmitate
• (a-4) Product obtained by saponification of a monodic acid diester with calcium hydroxide, "Wachs OP" (trade name) of Hoechst AG (melting point 81 ° C)
• (a-5) pentaerythritoltribehenate

example 1

dimethyl terephthalate and ethylene glycol were prepared by adding manganese acetate as a transesterification catalyst, Titantrimellitat as a polymerization catalyst, phosphoric acid as Stabilizer and 0.03% of globular Silica with an average particle diameter of 60 nm and a volume forming coefficient of 0.5 as a lubricant (inert particles E) polymerized to the resin by a conventional method, polyethylene terephthalate (resin B1) for the first thermoplastic layer (Thermoplastic layer B) having an intrinsic viscosity of 0.60.

Further dimethyl terephthalate and ethylene glycol were used in the same way as described above by adding spherical silica with a average particle diameter of 600 nm and θ-alumina with an average particle diameter of 60 nm as a lubricant (third inert particles or inert particles D) in amounts of 0.12% or 0.2% to the resin polymerized by a conventional method, polyethylene terephthalate having an intrinsic viscosity of 0.60 to obtain.

0.3% Sorbitan tristearate powder (mp 55 ° C) (a-1) was dissolved in 99.7% of the obtained polyethylene terephthalate and dispersed in a degassing twin-screw extruder Kneaded to polyethylene terephthalate (resin A1) for the second thermoplastic layer (Thermoplastic layer A) having an intrinsic viscosity of 0.59.

The Resins A1 and B1 obtained were dried at 170 ° C for 3 hours, two Supplied to extruders, at 280 to 300 ° C melted through a steel wire filter with an average opening of 11 μm with greater Accuracy filtered and separated by means of a Koextrusionsdüse Feeding channels like this laminated to each other, that the resin layer B on one side of the resin layer A made and cooled was to a 89 microns to obtain thick unstretched laminated thermoplastic film.

The obtained unstretched film was preheated, stretched to 3.3 times between low-speed and high-speed rolls at a film temperature of 100 ° C, and cooled to obtain a longitudinally stretched film. An aqueous coating solution having the following composition (in terms of solid content) (total solid content 1.0%) was kiss-coated on the side of the sheet B of the longitudinally stretched film to form a first coating layer.
Binder: Acrylic modified polyester (IN-170-6 from Takamatsu Yushi Co., Ltd.), 67%
Second inert fine particles (inert particles B): acrylic filler (average particle diameter 30 nm) (volume-forming coefficient 0.40) (MA02W of Nippon Shokubai Co., Ltd.), 6%
Surfactant X: (Nonion NS-208.5 from NOF Corporation), 1%
Surfactant Y: (Nonion NS-240 from NOF Corporation), 26%
Thickness of the first coating layer (after drying): 5 nm

Subsequently, the film was fed to a tenter to be stretched to 4.2 times in the transverse direction at 110 ° C. The obtained biaxially oriented film was heat-set with 220 ° C hot air for 4 seconds to obtain a laminated biaxially oriented polyester film having a total thickness of 6.4 μm and a thickness of the base layer (thermoplastic layer A) of 1.0 microns to obtain. The thicknesses of the thermoplastic layers A and B of this film were adjusted via the feed rates of the two extruders. This film had a surface roughness WRa of the thermoplastic sheet B of 1.7 nm, a Young's modulus in the longitudinal direction of 500 kg / mm ^2, and a Young's modulus in the transverse direction of 700 kg / mm ² . Further characteristic properties of this laminated film and the characteristic properties of a ferromagnetic thin film deposition magnetic tape obtained from this film are shown in Table 2.

Examples 2 and 4

laminated Thermoplastic films were obtained in the same manner as in Example 1, except that species, average particle diameter and amount of inert particles to be contained in the thermoplastic sheet A D and type and amount of (partially hydrolyzed) ester wax were changed as shown in Table 1 and that in the first thermoplastic no Particles were included. The characteristic properties of obtained films and the characteristic properties of The films obtained ferromagnet Dünnfilmdepositions magnetic tapes are shown in Table 2.

Example 3

A Laminated thermoplastic film was obtained in the same way as in Example 1, except that species, average particle diameter and amount of inert particles to be contained in the thermoplastic sheet A D changed were as shown in Table 1 and that in the first coating layer into the core-shell filler (core: crosslinked polystyrene, cover: Polymethylmethacrylate) (average particle diameter 30 nm, volume forming coefficient 0.45) of the type "SX8721 (D) -12" (trade name) of JSR Corporation changed were. The characteristic properties of the obtained film and the characteristic properties of a film obtained from the film Ferromagnetic thin film deposited magnetic tape are shown in Table 2.

Examples 5 and 6

Polyethylene-2,6-naphthalate (PEN) (resins A2 and B2) for the thermoplastic layers A and B were obtained in the same way as in Example 1, except that species, average particle diameter and amount of inert particles to be contained in the thermoplastic sheet A D and type and amount of (partially hydrolyzed) ester wax were changed as shown in Table 1 and that the equimolar amount of dimethyl-2,6-naphthalenedicarboxylate was used in place of the dimethyl terephthalate.

The Resins A2 and B2 were at 170 ° C for 6 hours dried, and the thickness of each layer was adjusted in the same way as in Example 1, to a 89 microns to obtain thick unstretched laminated thermoplastic film.

The The unstretched film obtained was preheated to 3.6 times between Low-speed and high-speed rollers at one Foil temperature of 135 ° C stretched and cooled, one in the longitudinal direction To obtain stretched film. An aqueous coating solution (total solids content 1.0%) having the composition shown in Table 1 (based on the Solid content) was applied to the side of the layer B in the longitudinal direction stretched film applied in the same manner as in Example 1.

Subsequently, the film was fed to a tenter to be stretched to 5.7 times in the transverse direction at 155 ° C. The obtained biaxially oriented film was heat-set with air at 200 ° C for 4 seconds to obtain a laminated biaxially oriented polyester film having a total thickness of 4.4 μm and a base layer thickness (Thermoplastic Layer A) of 0.6 μm. The thicknesses of the thermoplastic layers A and B of this film were adjusted via the feed rates of the two extruders. In Example 5, this film had a surface roughness WRa of the thermoplastic layer B of 0.9 nm, a Young's modulus in the longitudinal direction of 550 kg / mm ² and a Young's modulus in the transverse direction of 1050 kg / mm ² . In Example 6, the film had a surface roughness WRa of the thermoplastic layer B of 1.1 nm, a longitudinal Young's modulus of 550 kg / mm ^2, and a Young's modulus in the transverse direction of 1050 kg / mm ² . Further characteristic properties of the laminated films and the characteristics of ferromagnetic thin film deposition magnetic tapes obtained from the films are shown in Table 2.

Comparative Example 1

A laminated thermoplastic film was obtained in the same manner as in Example 1 except that no (partially saponified) ester wax was contained in the thermoplastic layer A. The resulting film adhered firmly and broke when forcibly released to measure its blocking peel force. Further characteristic properties of the film and the characteristic properties of a ferromagnetic thin film deposition magnetic tape obtained from the film are shown in Table 4.

Comparative Example 2

A Laminated thermoplastic film was obtained in the same way as in Example 1, except that the amount of sorbitan tristearate (a-1) changed to 12% has been. rejection gets on the backsheet the resulting film when applying a backside coating in the Step of producing a magnetic tape observed. Therefore could an ordinary one Coating not performed becomes. Other characteristic features of the film and the characteristic properties of a film obtained from the film Ferromagnetic thin film deposited magnetic tape are shown in Table 4.

Comparative Example 3

A Laminated thermoplastic film was obtained in the same way as in Example 1, except that 0.2% of spherical silica with a average particle diameter of 200 nm (volume-forming coefficient 0.5) as to be absorbed in the thermoplastic layer B inert particles E were added. The resulting film was in terms of their inferior to electromagnetic conversion properties because of the surface roughness WRa of the thermoplastic layer B outside within the scope of the present invention. Further characteristic Properties of the film and the characteristic properties of a ferromagnetic thin film deposition magnetic tape obtained from the film shown in Table 4.

Comparative Example 4

A Laminated thermoplastic film was obtained in the same way as in Example 5, except that no inert particles D in the Thermoplastic layer A were included. Because the film stuck tight, as their blocking peel force should be measured, the measurement could not be performed. Further characteristic properties of the film and the characteristic Properties of a ferromagnetic thin film deposition magnetic tape obtained from the film are shown in Table 4.

Comparative Example 5

A Laminated thermoplastic film was obtained in the same way as in Example 5, except that 0.2% sorbitan monoacetate in the Thermoplastic layer B were included. Because the film stuck tight, as their blocking peel force should be measured, the measurement could not be performed. Further characteristic properties of the film and the characteristic Properties of a ferromagnetic thin film deposition magnetic tape obtained from the film are shown in Table 4.

Out Table 2 is obvious that the laminated thermoplastic films according to the present Invention are very flat on one side and excellent electromagnetic Conversion properties and winding properties and high antiblocking properties demonstrate. Further - how from Table 4 - have laminated Thermoplastic films meeting the requirements of the present invention do not fulfill, not at the same time the above-mentioned characteristic properties on.

The Base film according to the present Invention is a laminated thermoplastic film which is excellent Anti-blocking properties, winding properties and processability and a metal deposition thin film magnetic recording medium provides excellent electromagnetic conversion properties having.

Claims (9)

Laminated thermoplastic base film for magnetic Recording media comprising: a first thermoplastic layer with a surface roughness WRa of the exposed surface from 0.1 to 4 nm; and a second thermoplastic layer, the 0.001 to 5 wt .-% of third inert fine particles with an average Particle diameter of the primary particles from 0.1 to 2.0 μm and 0.001 to 10 wt .-% of an ester wax from an aliphatic Monocarboxylic acid containing 8 or more carbon atoms and a polyhydric alcohol, and the one water contact angle the exposed surface from 70 to 90 °; in which the first thermoplastic layer and the second thermoplastic layer on each other laminated. The film of claim 1, further comprising a first coating layer comprising 0.5 to 30 wt .-% of second inert fine particles with an average particle diameter of the primary particles from 10 to 50 nm and a volume-forming coefficient of from 0.1 to π / 6, and the on the surface the first thermoplastic layer which does not interfere with the second thermoplastic layer in contact, is laminated. The film of claim 1, wherein the first thermoplastic layer essentially none from the outside added inert fine particles. The film of claim 1, wherein the first thermoplastic layer 0.001 to 0.2 wt .-% of inert fine particles with an average Particle diameter of the primary particles of 30 to 400 nm and a volume-forming coefficient of 0.1 to π / 6. The film of claim 1, wherein the first thermoplastic layer a polyester as a starting material. The film of claim 1, wherein the first thermoplastic layer Polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate as starting material. The film of claim 1, wherein the second thermoplastic layer a polyester as a starting material. The film of claim 1, wherein the second thermoplastic layer Polyethylene terephthalate or polyethylene-2,6-naphthalenedicarboxylate as starting material. A magnetic recording medium comprising a A base film comprising the laminated thermoplastic base film of claim 1, and the first coating layer according to claim 2, which the surface of the first thermoplastic layer which is not in contact with the second Thermoplastic layer stands, is laminated, and a magnetic layer, which is laminated to the first coating layer of the base film.